The present invention relates in general to low-resistance elongate boat or ship hulls for use in a single hull or multiple hull watercraft such as kayaks, catamarans, trimarans, or other watercraft.
A variety of different boat hull configurations have been developed for use in a variety of watercraft. Continued desire for increased speed and efficiency of boats drives further developments in boat hull configurations.
In certain prior art watercraft, the boat hull is substantially V-shaped for cutting through water when in use. Unfortunately, such V-shaped hulls often lack stability on the water. In other prior art watercraft such as catamarans, flat bottom hulls are employed for the purpose of providing a stable ride. Such hulls, however, provide this stable ride at the cost of speed when travelling on the water. Skin friction is high in these boats as a large surface area of the hull is in contact with the water. Similarly, resistance is high as water is displaced away from the hull forming waves as the hull moves through the water.
In still other prior art watercraft, channels are provided in the hull bottom for producing dynamic lift and trapping air for the purpose of lubricating the hull. Bulbous-nosed hulls have also been employed to reduce the amount of water that has to be accelerated by the bow by allowing water that is in the path of a moving hull to be moved around the hull in the direction of least resistance. The bow used in the present invention saves energy in a similar manner but does not protrude froward like a nose. Instead, the bow in the present invention is an integral part of the hull.
It is an object of an aspect of the present invention to provide a low-resistance hull configuration for single or multiple hull watercraft.
In one aspect, there is provided a hull configuration comprised of four components that together are greater than the sum of the individual parts. The hull configuration includes a concave bottom forming a channel, a pair of convex cutting edges, a pair of convex side edges and a pair of side walls.
In one aspect of the present invention, there is provided a hull configuration having a bow and a stern, for use in a single or multiple hull vessel. The hull configuration has a pair of cutting edges, each cutting edge sloping rearwardly, downwardly and in an outwardly lateral direction, from the bow. Each one of a pair of side edges, extends longitudinally rearwardly and laterally inwardly from an end of a respective one of the cutting edges and smoothly join together proximal the stern. Each one of a pair of sidewalls extends generally upwardly from respective ones of cutting edges and the rounded side edges, and together the sidewalls form a rounded V-shaped section from the point where the side edges meet, extending rearwardly to the stern. An underside includes a concave channel between the cutting edges and between the generally rounded side edges. The channel decreases in width towards the stern and terminates at the point at which the side edges meet.
Advantageously, skin friction of the boat hull is reduced by reducing the wetted surface area of the hull and by using air that is trapped in the channel to lubricate the hull. Also, the wave-making resistance of the hull is reduced by reducing the acceleration of water in the path of the moving hull. Drag is reduced by reducing the acceleration of the water which is dragged into the space that is vacated by the moving hull.
In one aspect, water is displaced and replaced simultaneously by allowing the movement of water to occur over the entire length of the hull. Water that is moved up by the bow and which is pushed down by the channel also fills in the space that is vacated by the moving hull. Drag is reduced while reducing wave-making resistance by allowing the water to flow from the channel around the convex sides into the space vacated by the moving hull. The water takes the path of least resistance and movement of the hull is facilitated by the convex sides of the hull.
The channel is widest near the bow and narrows down to a point near the stern.
The convex cutting edges are joined to the channel at the bottom, to the sidewalls at the top, to the side edges at their most forward ends and to each other ahead of the channel. At that point, they form the bow. They extend from the bow outwards and rearwards to the widest part of the channel. The cutting edges are widest at the bow and narrowest or sharpest at the opposite end, where they join the side edges.
The convex side edges are joined to the channel at the bottom, to the sidewalls at the top, to the cutting edges at their most rearward ends and to each other to the rear of the channel. At that point they form the stern. The convex side edges extend from the sharpest points of the cutting edges inwards and rearwards to join each other at the stern.
The sidewalls are joined to the top of the convex components, sloping inwardly and up near the bow, straight up at midship and outwards and up towards the stern.